Gear assembly for a wind turbine gearbox having a flexible pin shaft and carrier

ABSTRACT

A carrier and at least one pin shaft of a gearbox of a wind turbine and method of manufacturing same includes forming the carrier and the pin shaft(s) as a single part or separate components. Further, the method includes forming one or more voids in the pin shaft(s) and/or the carrier via additive manufacturing. As such, the void(s) is configured to increase flexibility of the pin shaft(s)/carrier so as to improve a load distribution thereof.

FIELD

The present disclosure relates in general to wind turbines, and moreparticularly to a gear assembly for a wind turbine gearbox having aflexible pin shaft and carrier made, at least in part, via additivemanufacturing.

BACKGROUND

Generally, a wind turbine includes a tower, a nacelle mounted on thetower, and a rotor coupled to the nacelle. The rotor generally includesa rotatable hub and a plurality of rotor blades coupled to and extendingoutwardly from the hub. Each rotor blade may be spaced about the hub soas to facilitate rotating the rotor to enable kinetic energy to beconverted into usable mechanical energy, which may then be transmittedto an electric generator disposed within the nacelle for the productionof electrical energy. Typically, a gearbox is used to drive the electricgenerator in response to rotation of the rotor. For instance, thegearbox may be configured to convert a low speed, high torque inputprovided by the rotor to a high speed, low torque output that may drivethe electric generator.

The gearbox generally includes a gearbox housing containing a pluralityof gears (e.g., planetary, ring and/or sun gears as well asnon-planetary gears) connected via one or more planetary carriers andbearings for converting the low speed, high torque input of the rotorshaft to a high speed, low torque output for the generator. In addition,each of the gears rotates about a pin shaft arranged within the one ormore planetary carriers. Lubrication systems are often used within thegearbox to circulate oil therethrough, thereby decreasing the frictionbetween the components of the gearbox as well as providing cooling forsuch components. In addition, the oil is configured to provide corrosionprotection while also flushing debris from the lubricated surfaces.

Deformation of many of the gearbox components results in a non-idealload distribution between the gears. Though all loaded components deformunder load, deformation of interfaces between the components is moredifficult to predict. The pin shafts of the gearbox therefore oftenrequire extensive machining. More particularly, the pin-end connectionsof the pin shafts, which are loaded in bending, can be problematic bydesign. Thus, such gearbox components can experience an uneven loaddistribution.

Accordingly, an improved gearbox assembly for a wind turbine thataddresses the aforementioned issues would be welcomed in the art.

BRIEF DESCRIPTION

Aspects and advantages of the invention will be set forth in part in thefollowing description, or may be obvious from the description, or may belearned through practice of the invention.

In one aspect, the present disclosure is directed to a method formanufacturing a gear assembly of a gearbox of a wind turbine. The methodincludes forming a carrier of the gear assembly and at least one pinshaft of the gear assembly as a single part. Further, the pin shaft(s)has a variable cross-section. The method also includes forming one ormore voids in the gear assembly via an additive manufacturing process.As such, the void(s) are configured to increase flexibility of the pinshaft(s) so as to improve a load distribution of the carrier.

In one embodiment, the additive manufacturing process may include binderjetting, material jetting, laser cladding, cold spray deposition,directed energy deposition, powder bed fusion, material extrusion, vatphotopolymerisation, or any other suitable additive manufacturingprocess.

In another embodiment, the method may include forming at least oneadditional feature into the pin shaft(s) via additive manufacturing.More specifically, in certain embodiments, the additional feature(s) mayinclude an oil path, one or more ribs or structural supports on andinterior surface of one or more of the voids, a cooling channel, aninspection path, a void removal feature, a signal wiring path, a sensorrecess, or a locating feature, or any other features that can be easilyprinted or formed therein.

In further embodiments, the method may include forming the carrier andthe pin shaft(s) as the single part via additive manufacturing.

In alternative embodiments, the step of forming the carrier and the pinshaft(s) may include casting the carrier and the pin shaft(s) as asingle part. In such embodiments, the step of casting the carrier andthe pin shaft(s) may include pouring a liquid material into a mold ofthe carrier and the pin shaft(s) and allowing the liquid material tosolidify in the mold so as to form the carrier and the pin shaft(s) asthe single part. Alternatively, the step of casting the carrier and thepin shaft(s) may include pouring a liquid material into a mold of thecarrier, allowing the liquid material to solidify in the mold so as toform the carrier, and then additively molding or printing the pinshaft(s) to the cast carrier to form the integral part.

In additional embodiments, the method may include splitting the carrierinto a main portion and a secondary portion after forming the carrierand the at least one pin shaft as the single part, the main portioncomprising the at least one pin shaft so as to assist with assembly ofthe gears onto the pin shaft(s). As such, after splitting, the methodmay include removing the secondary portion of the carrier from the mainportion and assembling a gear onto the pin shaft(s) of the main portion.The method then includes replacing the secondary portion onto the mainportion.

In several embodiments, the method may include determining a locationfor the one or more voids based on a load path of the carrier. Forexample, in one embodiment, the method may include forming the one ormore voids in the pin shaft(s) in a lengthwise center location thereofso as to load the gears as evenly as possible.

In particular embodiments, the method may also include depositing, e.g.printing, bearing material onto an exterior surface of the pin shaft(s).

In another aspect, the present disclosure is directed to a method formanufacturing a gear assembly of a gearbox of a wind turbine. The methodincludes forming a carrier of the gear assembly. The method alsoincludes forming at least one pin shaft of the gear assembly having avariable cross-section. Further, the method includes forming one or morevoids in the gear assembly via an additive manufacturing process.Moreover, the void(s) are configured to increase flexibility of the pinshaft(s) so as to improve a load distribution of the carrier. Inaddition, the method includes securing the pin shaft(s) to the carrier.

It should also be understood that the method may further include any ofthe additional features and/or steps described herein.

In addition, the step of forming the carrier and forming the pinshaft(s) may include casting the carrier and casting the pin shaft(s) asseparate parts. Thus, in certain embodiments, the method may includesecuring the pin shaft(s) to the carrier via one or more fasteners.

In further embodiments, the method may include depositing bearingmaterial onto an exterior surface of the pin shaft(s) and covering theone or more fasteners with the deposited bearing material.

In yet another aspect, the present disclosure is directed to a gearboxassembly. The gearbox assembly includes a gearbox housing and aplanetary gear system configured therein. The planetary gear systemincludes a plurality of planet gears, at least one sun gear, at leastone ring gear, at least one carrier operatively coupled with theplurality of planet gears, and a plurality of pin shafts. Each of theplanet gears is arranged so as to rotate around one of the plurality ofpin shafts. Further, each of the planet gears is engaged with the ringgear and configured to rotate about the sun gear. Further, the pinshaft(s) is integral with the carrier. Moreover, the pin shaft(s)includes a variable cross-section containing one or more voids formedtherein. As such, the variable cross-section of the pin shaft(s) isconfigured to increase flexibility of the pin shaft(s) so as to improvea load distribution of the carrier.

It should also be understood that the gearbox assembly may furtherinclude any of the additional features described herein.

In addition, the gearbox assembly may include at least one seal arrangedon an exterior surface of the pin shaft(s) so as to seal the one or morevoids, which may prevent swarf from entering the void(s) whilemachining. In addition, the seal(s) may also be arranged to guide theoil supply or the oil draining.

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdescription and appended claims. The accompanying drawings, which areincorporated in and constitute a part of this specification, illustrateembodiments of the invention and, together with the description, serveto explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth in the specification, which makes reference to the appendedfigures, in which:

FIG. 1 illustrates a perspective view of one embodiment of a windturbine according to conventional construction;

FIG. 2 illustrates a detailed, internal view of one embodiment of anacelle of a wind turbine according to conventional construction;

FIG. 3 illustrates a cross-sectional view of one embodiment of a gearboxassembly of a wind turbine according to conventional construction;

FIG. 4 illustrates a cross-sectional view of one embodiment of a gearboxassembly of a wind turbine according to the present disclosure;

FIG. 5 illustrates a detailed, cross-sectional view of one embodiment ofan integral planetary carrier and flexible pin shaft of the gearboxassembly assembled with the planet gear according to the presentdisclosure;

FIG. 6 illustrates a detailed, cross-sectional view of one embodiment ofan integral planetary carrier and flexible pin shaft of the gearboxassembly disassembled from the planet gear according to the presentdisclosure;

FIG. 7 illustrates a detailed, cross-sectional view of one embodiment ofa planetary carrier and a separate flexible pin shaft of the gearboxassembly according to the present disclosure, particularly illustratingthe pin shaft mounted to the planetary carrier;

FIG. 8 illustrates a detailed, cross-sectional view of one embodiment ofa planetary carrier and a separate flexible pin shaft of the gearboxassembly according to the present disclosure, particularly illustratingthe pin shaft dismounted from the planetary carrier; and,

FIG. 9 illustrates a detailed, cross-sectional view of one embodiment ofa separate flexible pin shaft of the gearbox assembly according to thepresent disclosure, particularly illustrating an oil path formedtherein;

FIG. 10 illustrates a front view of one embodiment of an integralplanetary carrier and a plurality of flexible pin shafts of the gearboxassembly according to the present disclosure;

FIG. 11 illustrates a detailed, cross-sectional view of one embodimentof a separate flexible pin shaft of the gearbox assembly according tothe present disclosure, particularly illustrating a non-conical voidformed therein;

FIG. 12 illustrates detailed, front views of a plurality of flexible pinshafts of the gearbox assembly according to the present disclosure,particularly illustrating different shapes of voids formed in the pinshafts;

FIG. 13 illustrates a detailed, cross-sectional view of one embodimentof a separate flexible pin shaft of the gearbox assembly according tothe present disclosure, particularly illustrating various additionalfeatures formed therein;

FIG. 14 illustrates a detailed, cross-sectional view of one embodimentof a separate flexible pin shaft of the gearbox assembly according tothe present disclosure, particularly illustrating a sensor wire path andsensor recess formed therein;

FIG. 15 illustrates a perspective view of one embodiment of a planetarycarrier and a plurality of integral pin shafts of a gearbox assemblyaccording to the present disclosure;

FIG. 16 illustrates a side view of the planetary carrier and theplurality of integral pin shafts of the gearbox assembly of FIG. 15;

FIG. 17 illustrates a cross-sectional view of the planetary carrier andthe plurality of integral pin shafts of the gearbox assembly of FIG. 16;

FIG. 18 illustrates a detailed, cross-sectional view of anotherembodiment of a flexible pin shaft of the gearbox assembly according tothe present disclosure, particularly illustrating various additionalfeatures formed therein; and

FIG. 19 illustrates a flow diagram of one embodiment of a method formanufacturing a gear assembly of a gearbox of a wind turbine accordingto the present disclosure.

DETAILED DESCRIPTION

Reference now will be made in detail to embodiments of the invention,one or more examples of which are illustrated in the drawings. Eachexample is provided by way of explanation of the invention, notlimitation of the invention. In fact, it will be apparent to thoseskilled in the art that various modifications and variations can be madein the present invention without departing from the scope or spirit ofthe invention. For instance, features illustrated or described as partof one embodiment can be used with another embodiment to yield a stillfurther embodiment. Thus, it is intended that the present inventioncovers such modifications and variations as come within the scope of theappended claims and their equivalents.

Generally, the present disclosure is directed to a gear assembly havingat least one flexible pin shaft and/or carrier and methods andmanufacturing same. It should be understood that the pin shaftsdescribed herein are meant to encompass any pin shafts within thegearbox, including pin shafts at planetary stages as well asnon-planetary stages (e.g. helical stages). In one embodiment, thecarrier and pin shaft(s) may be formed as an integral or single part.Alternatively, the carrier and pin shaft(s) may be formed as separatecomponents. In addition, the carrier and pin shaft(s) may be formed viacasting, additive manufacturing, or combinations thereof. Morespecifically, the flexible pin shaft(s) has a variable cross-sectionthat includes one or more voids formed via additive manufacturing.Further, the void(s) may also be formed into the carrier, e.g. adjacentto the pin shaft(s). As such, the void(s) are configured to increaseflexibility thereof so as to improve a load distribution of the carrier.

Thus, the present disclosure provides many advantages not present in theprior art. For example, the integral carrier/flexible pin shaft avoidsinterfaces between parts, thereby avoiding machining cost and/or boltingof the interfaces, handling of the extra parts, as well as the failuremodes of the interfaces or variance in the behavior of the interface dueto manufacturing tolerances allowed. Alternatively, the presentdisclosure may keep the carrier separate from flexible pin shaft, inwhich case the pin shaft can be formed via additive manufacturing andthe carrier may be formed via a more simplistic manufacturing process,such as casting, to take advantage of the different advantages of bothtechniques. In either case, the flexible pin shaft(s) provide a moreeven load distribution than pin shafts having a constant or uniformcross-section.

Referring now to the drawings, FIG. 1 illustrates a perspective view ofone embodiment of a wind turbine 10 of conventional construction. Asshown, the wind turbine 10 includes a tower 12 extending from a supportsurface 14, a nacelle 16 mounted on the tower 12, and a rotor 18 coupledto the nacelle 16. The rotor 18 includes a rotatable hub 20 and at leastone rotor blade 22 coupled to and extending outwardly from the hub 20.For example, in the illustrated embodiment, the rotor 18 includes threerotor blades 22. However, in an alternative embodiment, the rotor 18 mayinclude more or less than three rotor blades 22. Each rotor blade 22 maybe spaced about the hub 20 to facilitate rotating the rotor 18 to enablekinetic energy to be transferred from the wind into usable mechanicalenergy, and subsequently, electrical energy. For instance, the hub 20may be rotatably coupled to an electric generator 24 (FIG. 2) positionedwithin the nacelle 16 to permit electrical energy to be produced.

As shown, the wind turbine 10 may also include a turbine control systemor a turbine controller 26 centralized within the nacelle 16. Forexample, as shown in FIG. 2, the turbine controller 26 is disposedwithin a control cabinet mounted to a portion of the nacelle 16.However, it should be appreciated that the turbine controller 26 may bedisposed at any location on or in the wind turbine 10, at any locationon the support surface 14 or generally at any other location. Ingeneral, the turbine controller 26 may be configured to transmit andexecute wind turbine control signals and/or commands in order to controlthe various operating modes (e.g., start-up or shut-down sequences)and/or components of the wind turbine 10.

Referring now to FIG. 2, a simplified, internal view of a nacelle 16 ofthe wind turbine 10 according to conventional construction isillustrated. As shown, the generator 24 may be disposed within thenacelle 16. In general, the generator 24 may be coupled to the rotor 18of the wind turbine 10 for producing electrical power from therotational energy generated by the rotor 18. For example, as shown inthe illustrated embodiment, the rotor 18 may include a rotor shaft 32coupled to the hub 20 for rotation therewith. The rotor shaft 32 may, inturn, be rotatably coupled to a generator shaft 34 of the generator 24through a gearbox assembly 36. As is generally understood, the rotorshaft 32 may provide a low speed, high torque input to the gearboxassembly 36 in response to rotation of the rotor blades 22 and the hub20. The gearbox assembly 36 may then be configured to convert the lowspeed, high torque input to a high speed, low torque output to drive thegenerator shaft 34 and, thus, the generator 24. In alternativeembodiments, the rotor shaft 32 may be eliminated and the rotatable hub20 may be configured to turn the gears of the gearbox assembly 36,rather than requiring a separate rotor shaft 32.

Referring now to FIG. 3, a cross-sectional view of a gearbox assembly 36according to conventional construction is illustrated. As shown, thegearbox assembly 36 includes planetary gear system 38 housed within agearbox housing 37. More specifically, the gear system 38 includes aplurality of gears (e.g., planetary, ring, sun, helical, and/or spurgears) and bearings 39 for converting the low speed, high torque inputof the rotor shaft 32 to a high speed, low torque output for thegenerator 24. For example, as shown, the input shaft 32 may provide aninput load to the gear system 38 and the system 38 may provide an outputload to the generator 24 (FIG. 2) as is generally known in the art.Thus, during operation, input load at an input rotational speed istransmitted through the planetary gear system 38 and provided as outputload at output rotational speed to the generator 24.

Further, the planetary gear system 38 includes a first planetary carrier40 and a second planetary carrier 42 operatively coupling a plurality ofgears. Further, as shown, the planetary gear system 38 includes, atleast, a ring gear 41, one or more planet gears 44, a sun gear 46, oneor more first pin shafts 43, and one or more second pin shafts 45. Forexample, in several embodiments, the gear system 38 may include one,two, three, four, five, six, seven, eight, or more planet gears 44.Further, each of the gears 41, 44, 46 includes a plurality of teeth. Theteeth are sized and shaped to mesh together such that the various gears41, 44, 46 engage each other. For example, the ring gear 41 and the sungear 46 may each engage the planet gears 44. In addition, it should beunderstood that the gears 41, 44, 46 described herein may include anysuitable type of gears, including but not limited to spur gears, facegears, helical gears, double helical gears, or similar.

In some embodiments, one or both of the planetary carriers 40, 42 may bestationary. In these embodiments, the input shaft 32 may be coupled tothe ring gear 41, and input loads on the input shaft 32 may betransmitted through the ring gear 41 to the planet gears 44. Thus, thering gear 41 may drive the gear system 38. In other embodiments, thering gear 41 may be stationary. In these embodiments, the input shaft 32may be coupled to the planetary carriers 40, 42, and input loads on theinput shaft 32 may be transmitted through the planetary carriers 40, 42to the planet gears 44. Thus, the planetary carriers 40, 42 may drivethe gear system 38. In still further embodiments, any other suitablecomponent, such as the planet gear 44 or the sun gear 46, may drive thegear system 38.

Still referring to FIG. 3, the sun gear 46 defines a central axis 49,and thus rotates about this central axis 49. The ring gear 41 may atleast partially surround the sun gear 46, and be positioned along thecentral axis 49. Further, the ring gear 41 may (if rotatable) thusrotate about the central axis 49. Each of the planet gears 44 may bedisposed between the sun gear 46 and the ring gear 41, and may engageboth the sun gear 46 and the ring gear 41. For example, the teeth of thegears may mesh together, as discussed above. Further, each of the planetgears 44 may define a central planet axis 48, as shown. Thus, eachplanet gear 44 may rotate about its central planet axis 48.Additionally, the planet gears 44 and central planet axes 48 thereof mayrotate about the central axis 49.

The gearbox assembly 36 may also include a lubrication system or othermeans for circulating oil throughout the gearbox components. Forexample, as shown in FIG. 3, the gearbox assembly 36 may include aplurality of oil passages 47 that are configured to transfer oiltherethrough. As is generally understood, the oil may be used to reducefriction between the moving components of the gearbox assembly 36 andmay also be utilized to provide cooling for such components, therebydecreasing component wear and other losses within the gearbox assembly36 and increasing the lifespan thereof. In addition, the oil may containproperties that prevent corrosion of the internal gearbox components.

Referring now to FIG. 4, a cross-sectional view of a gearbox assembly136 according to the present disclosure is illustrated. As shown, thegearbox assembly 136 includes planetary gear system 138 housed within agearbox housing 137. More specifically, the gear system 138 includes aplurality of gears (e.g., planetary, ring and/or sun gears) and bearings139 for converting the low speed, high torque input of the rotor shaft132 to a high speed, low torque output for the generator (not shown).For example, as shown, the input shaft 132 may provide an input load tothe gear system 138 and the system 138 may provide an output load to thegenerator via output shaft 134. Thus, during operation, input load at aninput rotational speed is transmitted through the planetary gear system138 and provided as output load at output rotational speed to thegenerator.

Further, as shown, the planetary gear system 138 includes a firstplanetary carrier 140 and a second planetary carrier 142 operativelycoupling a plurality of gears. It should also be understood that theplanetary gear system 138 may have any suitable arrangement of planetarystages and/or helical stages. In the depicted embodiment, which isprovided for illustrated purposes only, the planetary gear system 138includes, at least, a ring gear 141, one or more planet gears 144, a sungear 146, one or more first pin shafts 143, and one or more second pinshafts 145. For example, in several embodiments, the gear system 138 mayinclude one, two, three, four, five, six, seven, eight, or more planetgears 144. Further, each of the gears 141, 144, 146 includes a pluralityof teeth. The teeth are sized and shaped to mesh together such that thevarious gears 141, 144, 146 engage each other. For example, the ringgear 141 and the sun gear 146 may each engage the planet gears 144. Inaddition, as mentioned, it should be understood that the gears 141, 144,146 described herein may include any suitable type of gears, includingbut not limited to spur gears, face gears, helical gears, double helicalgears, or similar.

In some embodiments, the planetary carriers 140, 142 may be stationary.In these embodiments, the input shaft 132 may be coupled to the ringgear 141, and input loads on the input shaft 132 may be transmittedthrough the ring gear 141 to the planet gears 144. Thus, the ring gear141 may drive the gear system 138. In other embodiments, the ring gear141 may be stationary. In these embodiments, the input shaft 132 may becoupled to the planetary carriers 140, 142, and input loads on the inputshaft 132 may be transmitted through the planetary carriers 140, 142 tothe planet gears 144.

Still referring to FIG. 4, the sun gear 146 defines a central axis 149,and thus rotates about this central axis 149. The ring gear 141 may atleast partially surround the sun gear 146, and be positioned along thecentral axis 149. For example, the ring gear 141 may be aligned with thesun gear 146 along the central axis 149, or may be offset from the sungear 146 along the axis 149. The ring gear 141 may (if rotatable) thusrotate about the central axis 149. Each of the planet gears 144 may bedisposed between the sun gear 146 and the ring gear 141, and may engageboth the sun gear 146 and the ring gear 141. In addition, as showngenerally in FIGS. 4-18, the pin shaft(s) 143, 145 and/or the planetarycarrier(s) 140, 142 of the present disclosure may include one or morevoids 152 formed therein so as to increase flexibility thereof, whichimproves the load distribution of the planetary carrier 140, 142. Thus,as shown, the pin shaft(s) 143, 145 may include a variable cross-sectionas opposed to a constant cross-section of prior art pin shafts.

Referring now to FIGS. 4-6, the pin shaft(s) 143, 145 of the presentdisclosure may be formed integrally with the planetary carrier 140, 142,respectively, (i.e. in contrast to conventional gearboxes as shown inFIG. 3 where the pin shaft(s) 43, 45 are separate from the planetarycarrier(s) 40, 42). In other words, in one embodiment, the pin shaft(s)143, 145 and the planetary carrier 140, 142 may be a formed as a singlepart. For example, in one embodiment, the pin shaft(s) 143, 145 may beformed integrally with the planetary carrier 140, 142 via an additivemanufacturing process. As used herein, additive manufacturing generallyrefers to processes used to create a three-dimensional object in whichlayers of material are formed under computer control to create anobject. More specifically, the additive manufacturing processesdescribed herein may include binder jetting, material jetting, lasercladding, cold spray deposition, directed energy deposition, powder bedfusion, material extrusion, vat photopolymerisation, or any othersuitable additive manufacturing process. In one exemplary embodiment,the pin shaft(s) 143, 145 may be formed integrally with the planetarycarrier 140 via sand binder jetting that utilizes ductile iron or carbonsteel.

In alternative embodiments, the pin shaft(s) 143, 145 may be formedintegrally with the planetary carrier 140, 142 via casting the pinshaft(s) 143, 145 and the planetary carrier(s) 140, 142 (e.g. the firststage planetary carrier 140 with a plurality of first stage pin shafts142) into a single mold. In such embodiments, casting of the planetarycarrier 140, 142 and the pin shaft(s) 143, 145 may include pouring aliquid material into a mold of the planetary carrier 140, 142 and thepin shaft(s) 143, 145 and allowing the liquid material to solidify inthe mold so as to form the planetary carrier 140, 142 and the pinshaft(s) 143, 145 as the single part. Alternatively, the planetarycarrier 140, 142 and the pin shaft(s) 143, 145 may be formed by pouringa liquid material into a mold of the planetary carrier 140, 142,allowing the liquid material to solidify in the mold so as to form theplanetary carrier 140, 142, and then additively molding or printing thepin shaft(s) 143, 145 to the cast carrier 140, 142 to form the integralpart.

In addition, as shown in FIGS. 15 and 16, the planetary carrier(s) 140,142 may be split into a main portion 151 and a secondary portion 153along split line 147 after it is formed to assist with assembly of thegears onto the pin shaft(s) 143, 145. Further, as shown, the mainportion 151 of the planetary carrier(s) 140, 142 may include the pinshaft(s) 143, 145. As such, after splitting, the secondary portion 153of the planetary carrier(s) 140, 142 from the main portion 151 such thatthe gears (not shown) can be assembled onto the pin shafts. Thesecondary portion 153 can then be secured to the main portion 151, e.g.via one or more fasteners.

Once the integral pin shaft(s) 143, 145 and planetary carrier(s) 140,142 is formed (or just the pin shaft(s) 143, 145), further additivemanufacturing techniques may be used to create the variablecross-section into the pin shaft(s) 143, 145. For example, as shown inFIGS. 4-9, an additive manufacturing process (e.g. such as sand binderjetting or lost wax casting methods) may be used to create the void(s)152 into the pin shaft(s) 143 and/or the carrier(s) 140, 142. As such,the variable cross-section of the pin shaft(s) 143, 145 is configured toincrease flexibility of the pin shaft(s) 143, 145 so as to improve aload distribution of the planetary carrier 140, 142. More specifically,as shown in FIGS. 4-10, the void(s) 152 may have a round, conical shapethat tapers from a first end 154 to a second end 156 of the pin shaft(s)143. Further, as shown particularly in FIG. 10, the flexible pin shafts143, 145 allow for the possibility to provide directional deformation(as represented by the arrows) that helps to improve the loaddistribution on the gears 144 and/or on the bearings (not shown). Asused herein, the term “variable cross-section” generally refers to anysuitably shaped cross-section that is non-uniform and/or non-constantover the length of the pin shaft(s) 143.

In alternative embodiments, as shown in FIG. 11, the void(s) 152 mayhave a non-conical shape. For example, as shown, the void(s) 152 may bethicker at the first and second ends 154, 156 and thinner in the middle.In addition, as shown in FIG. 12, it should be further understood thatthe void(s) 152 may have any suitable shape that may be adjusted tomatch the desired local stiffness. For example, as shown, FIG. 12illustrates three different cross-sections of a single representativepin shaft 143 along the longitudinal axis of the pin shaft 143. Thus, asshown, the cross-section of the pin shaft 143 (and more specifically thevoid 152) can be varied (e.g. rotated) axially to facilitate lowstresses along the load path. Accordingly, as shown, the cross-sectionof the void 152 of the pin shaft 143 may have a different shape alongthe axis to match the desired corresponding stiffness.

In additional embodiments, the location(s) for the void(s) 152 may bedetermined based on a load path of the planetary carrier(s) 140, 142.For example, in one embodiment, the void(s) 152 may be formed in the pinshaft(s) 143, 145 in a lengthwise center location thereof so as to movethe load path closer to the center of the pin shaft(s) 143, 145. Morespecifically, as shown in FIGS. 4-14, the voids(s) 152 taper towards thelengthwise center of the pin shaft(s) 143, 145 to maintain the stressesin the pin shaft(s) 143, 145 and the planetary carrier(s) 140, 142within acceptable limits while yielding deformation that creates adesired load pattern in the gears.

Referring particularly to FIGS. 13 and 14, at least one additionalfeature 160 may also be formed or printed into the pin shaft(s) 143 viaadditive manufacturing. More specifically, in certain embodiments, theadditional feature 160 may include an oil path (e.g. an oil supply path,an oil drain (removal) path, an oil distribution manifold, an oilcollection channel, an oil buffer, and/or similar), one or more ribs orstructural supports on and interior surface of one or more of the voids,a cooling channel, an inspection path, a void removal feature, a signalwiring path, one or more recesses, or a locating feature, or any otherfeatures that can be easily printed or formed therein.

For example, as shown in FIGS. 9 and 17-18, one or more oil paths 158may also be formed through the pin shaft(s) 143. More specifically, asshown particularly in FIG. 9, an oil path 158 may be formed from anexterior surface 155 of the pin shaft(s) 143 at the first end 154thereof and through one of the voids 152 to the second end 156 of thepin shaft(s) 143. In another embodiment, as shown in FIG. 17, the oilpath 158 may be completely separate from the voids 152. In furtherembodiments, any number of oil paths may be formed into the pin shaft(s)143, 145 via any suitable additive manufacturing process.

In additional embodiments, as shown in FIG. 13, the additionalfeature(s) 160 may also include a cooling channel 162. Further, as shownin FIGS. 17 and 18, the additional feature(s) 160 may include one ormore ribs 165 or structural supports on and interior surface of one ormore of the voids 152. Such ribs 165 are configured to locally increasestiffness where desired.

In addition, as shown in FIG. 14, the additional feature(s) 160 mayinclude a signal wiring path 164 and/or a sensor recess 166 configuredto receive a sensor or probe. Thus, as shown, a sensor wire andassociated sensor can be positioned in the pin shaft(s) 143. Further, asshown in FIG. 18, the additional feature(s) 160 may include aninspection path or probe recess configured to receive a proximity sensor(e.g. an inductive, infrared or ultrasonic sensor) that can takemeasurements of the curves at the end of the void(s) 152 opposite theplanetary carrier(s) 140, 142 as well as measuring pin deflection.

In further embodiments, the additional feature(s) 160 may include alocating feature 168. For example, as shown in FIGS. 5-6 and 13-14, thelocating features 168 may be flanges that assist in aligning the pinshaft(s) 143, 145 with the planetary carrier(s) 140, 142. It should beunderstood that the additional feature(s) 160 may further include anyother features that can be easily printed or formed therein.

In yet another embodiment, the additional feature(s) 160 may includevoid removal feature 169. For example, as shown in FIG. 18, one or moreof the voids 152 may be created to facilitate removal of sand binder jetcores used to cast the internal pin geometry. Such voids 152 arereferred to herein as void removal features 169. In addition, the pinshaft 142 may include additional number of additional recesses, such asrecess 174, configured to receive at least a portion of a bearing, suchas a journal or roller bearing frame. Further, as shown, the recess(es)174 may be designed to receive a retaining ring of a bearing.

Referring particularly to FIG. 13, the gearbox assembly 136 may furtherinclude at least one seal 170 arranged on the exterior surface 155 ofthe pin shaft(s) 143 so as to seal the one or more voids 152. In suchembodiments, the seal(s) 170 are configured to allow the voids 152 to bemulti-functional, e.g. to create a lubricant supply or drain, tofacilitate cleaning, and/or to prevent dirt out once cleaned, e.g.during machining or during operation.

Referring now to FIG. 19, a flow diagram of one embodiment of a method100 for manufacturing the planetary carrier 140 and the pin shaft(s) 143of the gearbox assembly 136 of the wind turbine 10 is illustrated. Asshown at 102, the method 100 includes forming the planetary carrier(s)140, 142. As shown at 104, the method 100 includes forming the pinshaft(s) 143, 145. For example, as shown in FIGS. 7 and 8, the planetarycarrier(s) 140, 142, and/or the pin shaft(s) 143, 145 may be formed viacasting the components as separate parts. It should be understood thatany suitable casting technique may be used, including but not limitedto, centrifugal casting, core plug casting, die casting, glass casting,investment casting, lost-foam casting, lost-wax casting, molding,permanent mold casting, rapid casting, sand casting, and/orslip-casting, etc.

As shown at 106, the method 100 includes forming one or more voids 152in the pin shaft(s) 143, 145 to create a variable cross-section of thepin shaft(s) 143, 145 via additive manufacturing. As such, the variablecross-section of the pin shaft(s) 143, 145 is configured to increaseflexibility of the pin shaft(s) 143, 145 so as to improve a loaddistribution of the planetary carrier 140, 142.

As shown at 108, the method 100 includes securing the pin shaft(s) 143,145 to the planetary carrier(s) 140, 142, respectively. Morespecifically, as shown in FIGS. 7, 9, 11, and 13-14, the method 100 mayinclude securing the pin shaft(s) 143, 145 to the planetary carrier(s)140, 142 via one or more fasteners 174.

In further embodiments, as shown FIGS. 13 and 14, the pin shaft(s) 143may further include bearing material 172 disposed onto the exteriorsurface 155 thereof. For example, in one embodiment, the method 100 mayinclude printing the bearing material 172 onto the exterior surface 155of the pin shaft(s) 143 layer by layer, e.g. so as to build up a journalbearing thereon. As such, the method 100 creates an adhesion ormetallurgical bond between the pin shaft(s) 143 and the bearing material172. Thus, the bond replaces conventional fasteners of prior art systemsand eliminates interference stresses, thereby enabling a smaller spaceenvelope. In addition, the method 100 requires less material/weight andreduces machining and assembly time for the journal bearing.

More specifically, in certain embodiments, the bearing material 172 mayinclude various metals or metal alloys, including, for example, a copperalloy (e.g. bronze). Thus, the bearing material 172 may be applied tothe exterior surface 155 of the pin shaft(s) 143 to provide improvedwear characteristics under loading (especially at startup and shutdown,when an oil film may be insufficient to separate the rotating andnon-rotating surfaces). In addition, as shown, the method 100 mayfurther include completely or partially covering the exterior surface155, thereby optionally covering the one or more fasteners 174 with thedeposited bearing material 172. Accordingly, by printing the bearingmaterial 172, said material can be thinner than conventional bearings(e.g. about 2 millimeters (mm) as opposed to 15 mm).

In certain embodiments, the bearing material 172 may be printed via aprogrammed robotic system capable of printing the bearing material 172that enables additional productivity benefits and repeatability relativeto a manual process. Traditionally, to harden the surface of thebearing, the entire journal would need to be heat treated. Hardening ofthe bearing is only needed on the surface and can be accomplished withconcentrated/amplified light energy. As such, the method 100 of thepresent disclosure improves speed and automation of the process andprovides optimal material properties only where desired.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they include structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

1. A method for manufacturing a gear assembly of a gearbox of a windturbine, the method comprising: forming a carrier of the gear assembly;additively molding or printing at least a portion of at least one pinshaft of the gear assembly onto the carrier to form an integral part,the at least one pin shaft having a variable cross-section; and, formingone or more voids in the gear assembly via an additive manufacturingprocess, the one or more voids configured to increase flexibility of theat least one pin shaft so as to improve a load distribution of thecarrier.
 2. The method of claim 1, wherein the additive manufacturingprocess comprises at least one of binder jetting, material jetting,laser cladding, cold spray deposition, directed energy deposition,powder bed fusion, material extrusion, or vat photopolymerisation. 3.The method of claim 1, further comprising forming at least oneadditional feature into the at least one pin shaft via additivemanufacturing, wherein the at least one additional feature comprises atleast one of an oil path, one or more ribs or structural supports on andinterior surface of one or more of the voids, a cooling channel, aninspection path, a void removal feature, a signal wiring path, a sensorrecess, or a locating feature.
 4. The method of claim 1, furthercomprising forming the carrier and the at least one pin shaft as thesingle part, at least in part, via additive manufacturing.
 5. The methodof claim 1, wherein forming the carrier of the gear assembly furthercomprises casting the carrier.
 6. The method of claim 5, wherein castingthe carrier of the gear assembly further comprises: pouring a liquidmaterial into a mold of the carrier; and, allowing the liquid materialto solidify in the mold so as to form the carrier.
 7. The method ofclaim 5, further comprising: splitting the carrier into a main portionand a secondary portion after casting the carrier, the main portionforming a base of the at least one pin shaft; removing the secondaryportion from the main portion; additively molding or printing an outerportion of the at least one pin shaft onto the base; assembling a gearonto the at least one pin shaft of the main portion; and, replacing thesecondary portion onto the main portion.
 8. The method of claim 1,further comprising determining a location for the one or more voidsbased on a load path of the carrier.
 9. The method of claim 1, furthercomprising forming the one or more voids in the at least one pin shaftin a lengthwise center location of the at least one pin shaft so as tomore evenly load gears of the gearbox.
 10. The method of claim 1,further comprising depositing bearing material onto an exterior surfaceof the at least one pin shaft. 11-18. (canceled)
 19. A gearbox assembly,comprising: a gearbox housing; and, a planetary gear system configuredwithin the gearbox housing, the planetary gear system comprising aplurality of planet gears, at least one sun gear, at least one ringgear, at least one carrier operatively coupled with the plurality ofplanet gears, and a plurality of pin shafts, each of the plurality ofplanet gears arranged so as to rotate around one of the plurality of pinshafts, the plurality of planet gears being engaged with the ring gearand configured to rotate about the sun gear, wherein the at least onepin shaft is integral with the carrier, the at least one pin shaft beingadditively molding or printing onto the carrier, the at least one pinshaft comprising a variable cross-section containing one or more voidsformed therein via an additive manufacturing process, the variablecross-section of the at least one pin shaft configured to increaseflexibility of the at least one pin shaft so as to improve a loaddistribution of the carrier.
 20. The gearbox assembly of claim 19,further comprising at least one seal arranged on an exterior surface ofthe at least one pin shaft.
 21. The gearbox assembly of claim 19,wherein the additive manufacturing process comprises at least one ofbinder jetting, material jetting, laser cladding, cold spray deposition,directed energy deposition, powder bed fusion, material extrusion, orvat photopolymerisation.
 22. The gearbox assembly of claim 19, furthercomprising at least one additional feature formed into the at least onepin shaft via additive manufacturing, wherein the at least oneadditional feature comprises at least one of an oil path, one or moreribs or structural supports on and interior surface of one or more ofthe voids, a cooling channel, an inspection path, a void removalfeature, a signal wiring path, a sensor recess, or a locating feature.23. The gearbox assembly of claim 19, wherein the one or more voids inthe at least one pin shaft are positioned in a lengthwise centerlocation of the at least one pin shaft so as to move the load pathtowards the lengthwise center location.
 24. The gearbox assembly ofclaim 19, further comprising one or more fasteners for further securingthe at least one pin shaft to the carrier.
 25. The gearbox assembly ofclaim 19, further comprising bearing material deposited onto an exteriorsurface of the at least one pin shaft and covering the one or morefasteners with the deposited bearing material.